1. Field of the Invention
The present invention relates to an image processing apparatus configured to combine original image data with copy-forgery-inhibited-pattern image data (hereinafter, referred to as “cfip” image data), and also relates to a control method for the image processing apparatus. Furthermore, the present invention relates to a storage medium configured to store a program enabling a computer to execute the control method for the image processing apparatus.
2. Description of the Related Art
The recent image processing devices, such as scanners, printers, and copying machines, have highly advanced performances that enable an unfair user to make an unauthorized copy of confidential documents, such as copy of official family registration or copy of written private contract. To prohibit such unauthorized copying of confidential documents or use of the copied documents, conventionally, security papers can be used for the printing of confidential documents.
The security papers are special papers including invisible patterns printed thereon beforehand. When a copying machine is used to make a copy of a security paper, the special pattern (e.g., warning letters) printed on the security paper will appear on the copy paper in a visible state.
The security papers can bring an effect of mentally inhibiting a user from making an unauthorized copy of confidential information, such as family registration information and contract information. Furthermore, warning letters appearing on the security paper can clearly differentiate the copy from the original.
Japanese Patent Application Laid-open No. 7-231384 proposes a method for producing a cfip image on an original as warning letters appearing in a visible state when the original is copied. According to this conventional method, when a scanner reads original image and the original image is copied by a recorder, a cfip image is produced and combined on the original image. Thus, ordinary papers are usable to obtain print results comparable to the results obtainable by the security papers.
As described later, the cfip image includes a latent area and a background area. An image of the latent area and an image of the background area, having common reflection density, are produced with different dither matrices.
According to the method discussed in Japanese Patent Application Laid-open No. 7-231384, an image combining section combines the original image and the cfip image. The image combining section and a cfip image producing section are positioned as post-processing sections for an image processing section of the original image. Therefore, the image processing for the original image does not need to be applied to the cfip image. Thus, the conventional method can prevent the cfip image from deteriorating.
Furthermore, Japanese Patent Application Laid-open 2001-346032 proposes a method for providing a transfer path dedicated to a cfip image and a buffer. The cfip image dedicated transfer path is different from a transfer path for the original image. Providing separately the original image transfer path and the cfip image dedicated transfer path can prevent the cfip image from being subjected to the image processing applied to the original image.
As described above, Japanese Patent Application Laid-open No. 7-231384 and Japanese Patent Application Laid-open 2001-346032 use a cfip image dedicated data bus to overcome the problem arising when the processing for the original image data is undesirably applied to the cfip image data. The processing applied to the original image data includes, for example, image processing and data compression/expansion processing.
However, the above-mentioned image processing apparatus including a cfip image dedicated data bus has a complicated structure and may be costly to produce.
In view of the foregoing, it is desired to provide an image processing apparatus that is capable of suppressing deterioration in the quality of the cfip image data and also desired to provide a related control method for the image processing apparatus.